scholarly journals Top1- and Top2-mediated topological transitions at replication forks ensure fork progression and stability and prevent DNA damage checkpoint activation

2007 ◽  
Vol 21 (15) ◽  
pp. 1921-1936 ◽  
Author(s):  
R. Bermejo ◽  
Y. Doksani ◽  
T. Capra ◽  
Y.-M. Katou ◽  
H. Tanaka ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Damage Checkpoint ◽  
Replication Forks ◽  
Checkpoint Activation ◽  
Topological Transitions

scholarly journals Disease-associated DNA2 nuclease–helicase protects cells from lethal chromosome under-replication

2020 ◽  
Author(s):  
Benoît Falquet ◽  
Gizem Ölmezer ◽  
Franz Enkner ◽  
Dominique Klein ◽  
Kiran Challa ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Damage ◽  
Cell Death ◽  
Dna Repair ◽  
Dna Damage Checkpoint ◽  
Replication Forks ◽  
Checkpoint Activation ◽  
Essential Function ◽  
Mutant Cells ◽  
Lagging Strand

Abstract DNA2 is an essential nuclease–helicase implicated in DNA repair, lagging-strand DNA synthesis, and the recovery of stalled DNA replication forks (RFs). In Saccharomyces cerevisiae, dna2Δ inviability is reversed by deletion of the conserved helicase PIF1 and/or DNA damage checkpoint-mediator RAD9. It has been suggested that Pif1 drives the formation of long 5′-flaps during Okazaki fragment maturation, and that the essential function of Dna2 is to remove these intermediates. In the absence of Dna2, 5′-flaps are thought to accumulate on the lagging strand, resulting in DNA damage-checkpoint arrest and cell death. In line with Dna2’s role in RF recovery, we find that the loss of Dna2 results in severe chromosome under-replication downstream of endogenous and exogenous RF-stalling. Importantly, unfaithful chromosome replication in Dna2-mutant cells is exacerbated by Pif1, which triggers the DNA damage checkpoint along a pathway involving Pif1’s ability to promote homologous recombination-coupled replication. We propose that Dna2 fulfils its essential function by promoting RF recovery, facilitating replication completion while suppressing excessive RF restart by recombination-dependent replication (RDR) and checkpoint activation. The critical nature of Dna2’s role in controlling the fate of stalled RFs provides a framework to rationalize the involvement of DNA2 in Seckel syndrome and cancer.

scholarly journals Slx4 Regulates DNA Damage Checkpoint-dependent Phosphorylation of the BRCT Domain Protein Rtt107/Esc4

2006 ◽  
Vol 17 (1) ◽  
pp. 539-548 ◽  
Author(s):  
Tania M. Roberts ◽  
Michael S. Kobor ◽  
Suzanne A. Bastin-Shanower ◽  
Miki Ii ◽  
Sonja A. Horte ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Damage Response ◽  
Dna Damage Checkpoint ◽  
Checkpoint Activation ◽  
Alkylation Damage ◽  
Binding Partner ◽  
Replication Restart ◽  
Damage Response ◽  
Domain Protein

RTT107 (ESC4, YHR154W) encodes a BRCA1 C-terminal-domain protein that is important for recovery from DNA damage during S phase. Rtt107 is a substrate of the checkpoint protein kinase Mec1, although the mechanism by which Rtt107 is targeted by Mec1 after checkpoint activation is currently unclear. Slx4, a component of the Slx1-Slx4 structure-specific nuclease, formed a complex with Rtt107. Deletion of SLX4 conferred many of the same DNA-repair defects observed in rtt107Δ, including DNA damage sensitivity, prolonged DNA damage checkpoint activation, and increased spontaneous DNA damage. These phenotypes were not shared by the Slx4 binding partner Slx1, suggesting that the functions of the Slx4 and Slx1 proteins in the DNA damage response were not identical. Of particular interest, Slx4, but not Slx1, was required for phosphorylation of Rtt107 by Mec1 in vivo, indicating that Slx4 was a mediator of DNA damage-dependent phosphorylation of the checkpoint effector Rtt107. We propose that Slx4 has roles in the DNA damage response that are distinct from the function of Slx1-Slx4 in maintaining rDNA structure and that Slx4-dependent phosphorylation of Rtt107 by Mec1 is critical for replication restart after alkylation damage.

scholarly journals The Yeast PCNA Unloader Elg1 RFC-Like Complex Plays a Role in Eliciting the DNA Damage Checkpoint

mBio ◽  
2019 ◽  
Vol 10 (3) ◽  
Author(s):  
Soumitra Sau ◽  
Batia Liefshitz ◽  
Martin Kupiec
Keyword(s):  
Dna Damage ◽  
Dna Replication ◽  
Cellular Response ◽  
Genome Stability ◽  
Adaptor Proteins ◽  
Nuclear Antigen ◽  
Dna Damage Checkpoint ◽  
Activation Process ◽  
Checkpoint Activation ◽  
Dna Replication And Repair

ABSTRACT The PCNA (proliferating cell nuclear antigen) ring plays central roles during DNA replication and repair. The yeast Elg1 RFC-like complex (RLC) is the principal unloader of chromatin-bound PCNA and thus plays a central role in maintaining genome stability. Here we identify a role for Elg1 in the unloading of PCNA during DNA damage. Using DNA damage checkpoint (DC)-inducible and replication checkpoint (RC)-inducible strains, we show that Elg1 is essential for eliciting the signal in the DC branch. In the absence of Elg1 activity, the Rad9 (53BP1) and Dpb11 (TopBP1) adaptor proteins are recruited but fail to be phosphorylated by Mec1 (ATR), resulting in a lack of checkpoint activation. The chromatin immunoprecipitation of PCNA at the Lac operator sites reveals that accumulated local PCNA influences the checkpoint activation process in elg1 mutants. Our data suggest that Elg1 participates in a mechanism that may coordinate PCNA unloading during DNA repair with DNA damage checkpoint induction. IMPORTANCE The Elg1protein forms an RFC-like complex in charge of unloading PCNA from chromatin during DNA replication and repair. Mutations in the ELG1 gene caused genomic instability in all organisms tested and cancer in mammals. Here we show that Elg1 plays a role in the induction of the DNA damage checkpoint, a cellular response to DNA damage. We show that this defect is due to a defect in the signal amplification process during induction. Thus, cells coordinate the cell's response and the PCNA unloading through the activity of Elg1.

53BP1: function and mechanisms of focal recruitment

2009 ◽  
Vol 37 (4) ◽  
pp. 897-904 ◽  
Author(s):  
Jennifer E. FitzGerald ◽  
Muriel Grenon ◽  
Noel F. Lowndes
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Dna Damage Response ◽  
Dna Damage Checkpoint ◽  
Checkpoint Activation ◽  
Damage Response ◽  
Nuclear Structures ◽  
Genotoxic Insult ◽  
Covalent Histone Modifications

53BP1 (p53-binding protein 1) is classified as a mediator/adaptor of the DNA-damage response, and is recruited to nuclear structures termed foci following genotoxic insult. In the present paper, we review the functions of 53BP1 in DNA-damage checkpoint activation and DNA repair, and the mechanisms of its recruitment and activation following DNA damage. We focus in particular on the role of covalent histone modifications in this process.

scholarly journals Regulation of E2F1 by BRCT Domain-Containing Protein TopBP1

2003 ◽  
Vol 23 (9) ◽  
pp. 3287-3304 ◽  
Author(s):  
Kang Liu ◽  
Fang-Tsyr Lin ◽  
J. Michael Ruppert ◽  
Weei-Chin Lin
Keyword(s):  
Dna Damage ◽  
Cell Cycle Progression ◽  
Specific Interaction ◽  
Dna Damage Checkpoint ◽  
Brct Domain ◽  
Replication Forks ◽  
Direct Role ◽  
Dna Topoisomerase ◽  
E2f Transcription Factor ◽  
Stalled Replication Forks

ABSTRACT The E2F transcription factor integrates cellular signals and coordinates cell cycle progression. Our prior studies demonstrated selective induction and stabilization of E2F1 through ATM-dependent phosphorylation in response to DNA damage. Here we report that DNA topoisomerase IIβ binding protein 1 (TopBP1) regulates E2F1 during DNA damage. TopBP1 contains eight BRCT (BRCA1 carboxyl-terminal) motifs and upon DNA damage is recruited to stalled replication forks, where it participates in a DNA damage checkpoint. Here we demonstrated an interaction between TopBP1 and E2F1. The interaction depended on the amino terminus of E2F1 and the sixth BRCT domain of TopBP1. It was specific to E2F1 and was not observed in E2F2, E2F3, or E2F4. This interaction was induced by DNA damage and phosphorylation of E2F1 by ATM. Through this interaction, TopBP1 repressed multiple activities of E2F1, including transcriptional activity, induction of S-phase entry, and apoptosis. Furthermore, TopBP1 relocalized E2F1 from diffuse nuclear distribution to discrete punctate nuclear foci, where E2F1 colocalized with TopBP1 and BRCA1. Thus, the specific interaction between TopBP1 and E2F1 during DNA damage inhibits the known E2F1 activities but recruits E2F1 to a BRCA1-containing repair complex, suggesting a direct role of E2F1 in DNA damage checkpoint/repair at stalled replication forks.

scholarly journals Repo-Man Controls a Protein Phosphatase 1-Dependent Threshold for DNA Damage Checkpoint Activation

2010 ◽  
Vol 20 (5) ◽  
pp. 387-396 ◽  
Author(s):  
Aimin Peng ◽  
Andrea L. Lewellyn ◽  
William P. Schiemann ◽  
James L. Maller
Keyword(s):  
Dna Damage ◽  
Protein Phosphatase ◽  
Protein Phosphatase 1 ◽  
Dna Damage Checkpoint ◽  
Checkpoint Activation

scholarly journals Phosphorylation of the Budding Yeast 9-1-1 Complex Is Required for Dpb11 Function in the Full Activation of the UV-Induced DNA Damage Checkpoint

2008 ◽  
Vol 28 (15) ◽  
pp. 4782-4793 ◽  
Author(s):  
Fabio Puddu ◽  
Magda Granata ◽  
Lisa Di Nola ◽  
Alessia Balestrini ◽  
Gabriele Piergiovanni ◽  
...  
Keyword(s):  
Dna Damage ◽  
Budding Yeast ◽  
Dna Damage Checkpoint ◽  
Checkpoint Activation ◽  
Checkpoint Response ◽  
Checkpoint Proteins ◽  
M Phase ◽  
Mutant Cells ◽  
Full Activation

ABSTRACT Following genotoxic insults, eukaryotic cells trigger a signal transduction cascade known as the DNA damage checkpoint response, which involves the loading onto DNA of an apical kinase and several downstream factors. Chromatin modifications play an important role in recruiting checkpoint proteins. In budding yeast, methylated H3-K79 is bound by the checkpoint factor Rad9. Loss of Dot1 prevents H3-K79 methylation, leading to a checkpoint defect in the G1 phase of the cell cycle and to a reduction of checkpoint activation in mitosis, suggesting that another pathway contributes to Rad9 recruitment in M phase. We found that the replication factor Dpb11 is the keystone of this second pathway. dot1Δ dpb11-1 mutant cells are sensitive to UV or Zeocin treatment and cannot activate Rad53 if irradiated in M phase. Our data suggest that Dpb11 is held in proximity to damaged DNA through an interaction with the phosphorylated 9-1-1 complex, leading to Mec1-dependent phosphorylation of Rad9. Dpb11 is also phosphorylated after DNA damage, and this modification is lost in a nonphosphorylatable ddc1-T602A mutant. Finally, we show that, in vivo, Dpb11 cooperates with Dot1 in promoting Rad9 phosphorylation but also contributes to the full activation of Mec1 kinase.

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